Typical requirements for a fuel injector require that it be able to withstand numerous hours of corrosive salt spray environment and still display no unsightly visible signs, such as rusting of exposed metal. Past anti-rust measures have included plating the exterior of metal parts of the injector, painting the exterior, or utilizing stainless steel metal.
Plating and painting require careful process control to insure that an even thickness of plating/painting occurs only in the areas desired: surface preparation and cleanliness can be a concern, and uneven covering of the surface results in failure to protect from corrosion. If the plating is applied prior to assembly of subcomponents, contamination of the interior of the injector can result in failed durability or leaking units. Plating or painting after subassembly means subjecting the final calibrated and flowed injector to mishandling or contamination issues which could also result in failed units. Additionally, one area of an injector where it is typically difficult to insure corrosion protection is the mating area between the power group and the valve group.
Although the plating or painting does not involve adding an additional separate "component," this is an extra process, typically requiring expertise in chemical mixing or adhesion. The extra steps of routing, and the associated cost of utilizing specialists can be expensive. Furthermore, continued emphasis on environmental issues involving recycling of old products has made several of the more proven plating solutions unavailable for future use.
Utilizing stainless steel for exterior injector components is another traditional solution for enhancing corrosion protection, but stainless carries drawbacks in that tool wear and material cost can be prohibitive.
The present invention relates to a low cost, snap- or press-on plastic shell component to provide the corrosion protection for the lower end of the fuel injector. Due to the structural embodiment of the concept, the shell can successfully cover varying amounts of exposed steel that tend to be present with any component stack-up situation.
Various features, advantages and the inventive aspects will be seen in the ensuing description and claims which are accompanied by drawings that disclose a presently preferred exemplary embodiment of the invention according to the best mode contemplated at the present time for carrying out the invention.